The development of high power thyristors for power system applications

It is only about 30 years since the thyristor was developed and since then advances in semiconductor technology have given rise to devices of ever-increasing size and switching capability (e.g. the switching power has doubled ever 2¹/₂ years). These developments are shown and described in detail. In order to switch power levels in the Multi-Megawatt region of interest for power system applications (e.g. 2000 MW for the Cross-Channel HVDC Scheme), parallel and series connection of devices is necessary. The authors discuss thyristor performance requirements, in particular series string operation. Applications in HVDC values and static compensators are discussed as are future developments in light triggered and GTO thyristors